Premier League clubs passed a temporary rule on Monday to stop teams from agreeing sponsorship deals with companies linked to their owners, sources have told ESPN, in a move that could restrict Newcastle United‘s new Saudi owners.

First reported by the Guardian, Newcastle and Manchester City were the only two clubs to vote against the proposals, which will be in force for one month. Newcastle’s legal team have argued that the amendment is unlawful.

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Financial Fair Play rules state that clubs must restrict their spending based on their revenue — which includes sponsorship deals. However, sponsorships involving companies linked to club owners have come under scrutiny, with City facing a Premier League investigation into their deal with United Arab Emirates company Etihad Airways.

City, who are owned by Abu Dhabi’s Sheikh Mansour, have denied wrongdoing.

Earlier this month, a Saudi Arabia-led takeover of Newcastle was completed with the Public Investment Fund (PIF) buying the Premier League club from previous owner Mike Ashley in a deal worth just over £300 million.

The Premier League, who came under pressure to block the deal last year, said it had received “legally binding” assurances that there was clear separation between PIF and the kingdom of Saudi Arabia, despite PIF being chaired by the Saudi Crown Prince Mohammed bin Salman.

The club’s new owners oversaw their first league match on Sunday in a 3-2 defeat to Tottenham Hotspur at St James’ Park.

Information from Reuters contributed to this report.